SEOUL, Oct. 2 (Yonhap) -- The finance minister and an opposition lawmaker on Tuesday clashed over a budget records leak at a parliamentary interpellation session.

Rep. Shim Jae-chul of the main opposition Liberty Korea Party (LKP) is under probe over an allegation that the lawmaker's aides accessed digital files on the fiscal budget and other confidential state statistics without authorization.

The finance ministry lodged a complaint against them with prosecutors last week for alleged illegal access of government information. In a tit-for-tat action, the LKP filed a complaint of its own against a vice finance minister.

Finance Minister Kim Dong-yeon and Shim exchanged barbs over the allegation when Shim took the podium at the parliamentary session on the economy.

Shim demonstrated how he accessed the digital files via dBrain, the online network on the government's budget and accounting. He slammed the government for failing to manage such information properly.

"My aides did not use illegal means, including hacking, to access the data," he claimed. "Access to the data was possible because it was open. Is the government viewing me as a criminal just because I logged in to data?," he said. "The government is trying to pass the buck of its failure to manage information to me," he said.

The finance minister denounced the lawmaker's alleged illegal downloading of the data.

"You keep talking about the information that was illegally taken," Kim said. "Digital files contained a warning message that stated access was limited to an audit office, but you ignored that and accessed the data. It was clearly wrong to make more than one million downloads."

The minister said that it is better for law enforcement authorities to make a judgment as the investigation is underway.

The case has emerged as a major point of contention in the ongoing parliamentary regular session at a time when the ruling party needs cooperation from opposition parties to ratify the April inter-Korean summit deal.

The row further intensified after Shim claimed Thursday that Cheong Wa Dae spent some 240 million won (US$215,750) in operational expenses improperly at nighttime and on weekends between May 2017 and August 2018.

The presidential office rebutted his claim. It said it is inevitable for its officials to handle state affairs beyond business hours, given that the nature of their work requires urgency and security and trade issues call for around-the-clock readiness.

Shim listed examples of the government and Cheong Wa Dae's suspected improper use of the national budget, including spending at bars when disasters occurred.

Kim rebutted Shim's claim, citing the record of his business operational expenses.

The LKP said that Shim's act was in the realm of ordinary political activity as a lawmaker. But the ruling Democratic Party insisted that the lawmaker and his aides are suspected of systemically leaking data, which it said amounts to a crime.